摘要:
A field emission electron gun (10) is disclosed which has an extraction electrode, composed of one or more sharply pointed electrode tips (17) in close proximity to a field emission cathode tip (11), such that a relatively low voltage between the cathode tip (11) and the extraction electrode tips (17), in the range of 100 to 2000 volts, will cause field emission of electrons from the cathode tip due to the extremely high localized electric field at the cathode tip. The electrons in the beam extracted from the cathode (11) are at a relatively low kinetic energy, particularly adapting the beam for use in such applications as low energy electron microscopy and low energy electron diffraction. For such applications, the extracted beam is generally passed through a limiting aperture member (21), electrostatic lenses (24, 25), and a deflection coil (26) when scanning of the target (27) is desired.
摘要:
Disclosed are propellants such as may be used in solid rocket motors. In one preferred embodiment, the propellant comprises one high energy propellant composition comprising a homogeneous mixture of fuel and oxidizer having a predetermined fuel/oxidizer ratio, wherein individual fuel particles are generally uniformly distributed throughout a matrix of oxidizer, and a low energy propellant composition comprising a fuel and oxidizer. The amounts of the two propellants are present in amounts which achieve a preselected burn rate.
摘要:
Disclosed are compositions comprising mixtures of metallic particles and solid oxidizer, and a method for preparing such compositions. The compositions comprise a homogeneous mixture of metallic particles and solid oxidizer wherein individual metallic particles are generally uniformly distributed throughout a matrix of solid oxidizer which is suitable for use in a solid rocket motor.
摘要:
A method for providing chemical energy and energetic compositions of matter consisting of thin layers of substances which will exothermically react with one another. The layers of reactive substances are separated by thin layers of a buffer material which prevents the reactions from taking place until the desired time. The reactions are triggered by an external agent, such as mechanical stress or an electric spark. The compositions are known as metastable interstitial composites (MICs). This class of compositions includes materials which have not previously been capable of use as energetic materials. The speed and products of the reactions can be varied to suit the application.
摘要:
A solid rocket motor for accelerating a payload comprises a motor casing and a solid propellant matrix, utilizing a high burn-rate fuel. The use of a high burn rate fuel allows the rocket motor to operate in an end-burning fashion without the use of a constricting aperture to increase the back-pressure upon the burn-front of the fuel matrix. The exhaust gas produced from combustion of the propellant matrix exits directly to the ambient environment through a simple aperture without the use of an expansion nozzle. By eliminating the mass of the nozzle and allowing the use of lighter, less structurally robust motor casings, the needed acceleration of the vehicle can be achieved while using less propellant and a lighter launch vehicle.
摘要:
A lead-free percussion primer composition and a percussion cup containing e composition. The lead-free percussion primer composition is comprised of a mixture of about 45 wt % aluminum powder having an outer coating of aluminum oxide and molybdenum trioxide powder or a mixture of about 50 wt % aluminum powder having an outer coating of aluminum oxide and polytetrafluoroethylene powder. The aluminum powder, molybdenum trioxide powder and polytetrafluoroethylene powder has a particle size of 0.1 .mu.m or less, more preferably a particle size of from about 200-500 angstroms.
摘要:
A method for providing chemical energy and energetic compositions of matter consisting of thin layers of substances which will exothermically react with one another. The layers of reactive substances are separated by thin layers of a buffer material which prevents the reactions from taking place until the desired time. The reactions are triggered by an external agent, such as mechanical stress or an electric spark. The compositions are known as metastable interstitial composites (MICs). This class of compositions includes materials which have not previously been capable of use as energetic materials. The speed and products of the reactions can be varied to suit the application.
摘要:
An apparatus for the measurement of the critical current of a superconductive sample, e.g., a clad superconductive sample, the apparatus including a conductive coil, a means for maintaining the coil in proximity to a superconductive sample, an electrical connection means for passing a low amplitude alternating current through the coil, a cooling means for maintaining the superconductive sample at a preselected temperature, a means for passing a current through the superconductive sample, and, a means for monitoring reactance of the coil, is disclosed, together with a process of measuring the critical current of a superconductive material, e.g., a clad superconductive material, by placing a superconductive material into the vicinity of the conductive coil of such an apparatus, cooling the superconductive material to a preselected temperature, passing a low amplitude alternating current through the coil, the alternating current capable of generating a magnetic field sufficient to penetrate, e.g., any cladding, and to induce eddy currents in the superconductive material, passing a steadily increasing current through the superconductive material, the current characterized as having a different frequency than the alternating current, and, monitoring the reactance of the coil with a phase sensitive detector as the current passed through the superconductive material is steadily increased whereby critical current of the superconductive material can be observed as the point whereat a component of impedance deviates.